In the 2007 findings, overall, a large majority of the American public were personally convinced that global warming is happening (71%). Surprisingly, however, only 48 percent believed that there is consensus among the scientific community, while 40 percent of Americans believed there is a lot of disagreement among scientists over whether global warming is occurring. Thus, many Americans appeared to have already made up their minds, without waiting for a perceived scientific consensus. Further, 69 percent of Americans believed that global warming is caused mainly by human activities (57%), or caused equally by humans and natural changes (12%), while only 29 percent believed it is caused mostly by natural changes in the environment.

Americans were evenly split, however, on their level of worry about global warming, with 50 percent personally worried either a great deal (15%) or a fair amount (35%) vs. 50 percent worried only a little (28%) or not at all (22%). These levels of personal worry were due in part to the fact that many Americans believe global warming is a serious threat to other species, people and places far away, but not so serious of a threat to themselves, their own families, or local communities.

Over the past few years, American perceptions that global warming is currently or will soon have dangerous impacts on people around the world have increased significantly. This survey found that 48 percent of Americans believed that global warming is already having dangerous impacts on people (30%) or will within the next ten years (18%): a 20 percentage point increase since the question was last asked in a nationally representative survey in June, 2004. Surprisingly, a large majority of Americans (62%) believed that global warming is an urgent threat requiring immediate and drastic action.